The first development of successful internal combustion engines occurred in the eighteenth and nineteenth centuries. The four stroke engine has developed as the most efficient at intaking the fuel-air mixture and exhausting the waste gases. A major disadvantage of the conventional four stroke engine is the large number of moving parts used to control the timed operation of the intake and exhaust valves. The large number of parts results in increased manufacturing and maintenance costs.
Those concerned with these and other problems recognize the need for an improved internal combustion engine.